Neonatal vaccination against respiratory syncytial virus infection

Respiratory syncytial virus (RSV) is the leading cause of pneumonia and bronchiolitis in infants and is the most frequent cause of lower respiratory tract infections in children. Efficacious vaccination has been a longstanding goal in neonates. Due to immaturity of the neonatal immune system, vaccination has shown limited success in stimulating the neonatal endogenous immune system. Advances in the understanding of neonatal immunology have resulted in renewed development of neonatal vaccination. In this article, we review recent advances in neonatal anti-RSV vaccination strategies, including active and passive vaccination approaches, with emphasis on the effect of maternal neutralizing antibody and the role of maternal antibody in neonatal immune modulations. Recent reports in a variety of antiviral vaccine animal models have shown that maternal antibody, different from conventional vaccination, plays an immune modulatory role in the newborn immune system. Active immunization of the pregnant mother and the offspring can effectively stimulate and maintain potent neonatal immune responses, including an endogenous cytotoxic response and neutralizing antibody generation. The induced newborn endogenous antiviral immunity can last up to 6 months, and effectively blunt viral replication. Immune complexes, formed from the integral binding of the maternal neutralizing antibody and viral vaccine antigen, may play an important role in the maternal antibody-mediated neonatal immune response. The underlying mechanisms and future perspectives are discussed.